#3和#11TLE，求助

#include <bits/stdc++.h>
using namespace std;
int n, m, startx, starty;
int a[1005][1005];
int b[1005][1005];
int step[1005][1005];
int vis[1005][1005];

struct point {
	int x;
	int y;
};
queue<point> r;

int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
char ch;
int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);
	std::cout.tie(0);
	cin >> n >> m;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= n; j++) {
			cin >> ch;
			if (ch == '1')
				a[i][j] = 1;
			else
				a[i][j] = 0;
		}
	}
	for (int i = 0; i <= n + 1; i++) {
		a[i][0] = 2;
		b[i][0] = 2;
		vis[i][0] = 2;
		a[i][n + 1] = 2;
		b[i][n + 1] = 2;
		vis[i][n + 1] = 2;
	}
	for (int i = 0; i <= n + 1; i++) {
		a[0][i] = 2;
		b[0][i] = 2;
		vis[0][i] = 2;
		a[n + 1][i] = 2;
		b[n + 1][i] = 2;
		vis[n + 1][i] = 2;
	}
	while (m--) {
//		memset(vis, 0, sizeof(int));
		int tstep = 1;
		cin >> startx >> starty;
		//bfs
		if (b[startx][starty] == 0) {
			for (int i = 1; i <= n; i++) {
				for (int j = 1; j <= n; j++) {
					vis[i][j] = 0;
				}
			}
			point start;
			start.x = startx;
			start.y = starty;
			r.push(start);
			b[startx][starty] = 2;
			vis[startx][starty] = 2;
			while (!r.empty()) {
				int x = r.front().x, y = r.front().y;
				for (int i = 0; i <= 3; i++) {
					int tx = x + dx[i];
					int ty = y + dy[i];
					if (a[x][y] == 1 && a[tx][ty] == 0 && vis[tx][ty] != 2) {
						point temp;
						temp.x = tx;
						temp.y = ty;
						tstep++;
						r.push(temp);
						b[tx][ty] = 2;
						vis[tx][ty] = 2;
					} else if (a[x][y] == 0 && a[tx][ty] == 1 && vis[tx][ty] != 2) {
						point temp;
						temp.x = tx;
						temp.y = ty;
						tstep++;
						r.push(temp);
						b[tx][ty] = 2;
						vis[tx][ty] = 2;
					}
				}
				r.pop();
			}
			for (int i = 1; i <= n; i++) {
				for (int j = 1; j <= n; j++) {
//					cout << vis[i][j];
					if (vis[i][j] == 2 && tstep > step[i][j]) {
						step[i][j] = tstep;
					}
				}
			}
//			for (int i = 1; i <= n; i++) {
//				for (int j = 1; j <= n; j++) {
//					cout << vis[i][j];
//				}
//				cout << endl;
//			}
			cout << tstep << endl;
		} else {
			cout << step[startx][starty] << endl;
//			for (int i = 1; i <= n; i++) {
//				for (int j = 1; j <= n; j++) {
//					cout << vis[i][j];
//				}
//				cout << endl;
//			}
		}
	}
	return 0;
}